©
National Instruments
11-1
X Series User Manual
11
Triggering
A trigger is a signal that ca
u
ses an action, s
u
ch as starting or stopping the
acq
u
isition of data. When yo
u
config
u
re a trigger, yo
u
m
u
st decide how
yo
u
want to prod
u
ce the trigger and the action yo
u
want the trigger to ca
u
se.
All X Series devices s
u
pport internal software triggering, as well as
external digital triggering. Some devices also s
u
pport analog triggering.
For information abo
u
t the different actions triggers can perform for each
s
u
b-system of the device, refer to the following sections:
•
The
Analog Input Triggering
section of Chapter 4,
Analog Input
•
The
Analog Output Triggering
section of Chapter 5,
Analog Output
•
The
Counter Triggering
section of Chapter 7,
Counters
Note
Not all X Series devices s
u
pport analog triggering. For more information abo
u
t
triggering compatibility, refer to the specifications doc
u
ment for yo
u
r device.
Triggering with a Digital Source
Yo
u
r DAQ device can generate a trigger on a digital signal. Yo
u
m
u
st
specify a so
u
rce and an edge. The digital so
u
rce can be any of the PFI,
RTSI, or PXI_STAR signals.
The edge can be either the rising edge or falling edge of the digital signal.
A rising edge is a transition from a low logic level to a high logic level.
A falling edge is a high-to-low transition.
Fig
u
re 11-1 shows a falling-edge trigger.
Figure 11-1.
Falling-Edge Trigger
5 V
0 V
F
a
lling Edge Initi
a
te
s
Acq
u
i
s
ition
Digit
a
l Trigger
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